Since the greenhouse effect of SF

6

gas

it became a common view that less SF

6

gas would be used in future. Spectra of SF

6

/N2 in short gap are studied in this paper from the perspective of SF

6

mixtures gas. Spectra of SF

6

/N

2

has been measured in uniformi

ty electric field

the pressure is between 0.1 MPa and 0.4 MPa. Spectrometer is used to measure microcosmic parameters like electron temperature and electron number density when SF

6

and mixture gas are completely breakdown. Then the relationships between these microcosmic parameters and macroscopic parameters（pressure

mix ratio

gap distance） are established

and breakdown characteristics of gas are analyzed from views of macroscopic and microcosmic. The study shows that when the gas is completely breakdown in a uniform electric field and the pressure between 0.1 MPa and 0.4 MPa

average electron temperature drops with pressure increasing from 6.06×10

4

K to 2.67×10

4

K

while electron number density rise from 3.15 ×10

17

m

-3

to 6.91 ×10

17

m

-3

with pressure increasing. Keep the pressure is 0.1 MPa

when the SF

6

/N

2

mixture gas is completely breakdown average electron temperature rise from 1.17 ×10

4

K to 6.06 ×104K with SF

6

mixture gas ratio increasing

while electron number density drops from 5.94 ×10

17

m

-3

to 3.15 ×10

17

m

-3

with SF

6

mixture gas ratio increasing.